Devices for removing jammed rock drill bits



Oct. 9, w56 w. J. BoEHNKE 2,765,777

DEVICES FOR RENOVING JAMMED ROCK DRILL BITS Filed Feb, l5, 1954 @Nil 1N V EN TOR.

W 'ZZ .Zvehn e fz/5,4, B5 am in AT TOZNEYS DEVICES FOR REMOVING JAIVIMED ROCK DRILL BITS This invention relates to devices for removing jammed rock drill bits.

While drilling blast holes in a rock face for the insertion of dynamite, the drill bits often become jammed causing considerable delay while attempts are made to remove them. Frequently it is not possible to free the bit by known methods and it and the hole must then be abandoned. Although the bits themselves are rather expensive and worthwhile expending time and elort to recover, the most important thing is the blast hole which costs a considerable amount to drill as well as taking a good deal of time. The conventional method of freeing the bit is to drill a second hole alongside the iirst and blast out at least a portion of the rock between the holes in an etlort to loosen the end of the bit. Obviously this is a time consuming and expensive operation which in many instances fails to free the bit.

Jamming of the drill bit is usually caused by clay or States Patent ground and powdered rock packing around the flared end of the cutting surface within a deep blast hole. A longitudinal hole is provided for passing compressed air through the bit during the time the blast hole is being drilled in order to blow out the rock that has been ground up; however, there is no fixed connection between the end of the jack hammer and the end of the bit and most of the air escapes resulting in too little air passing through the bit to raise the residue to the surface of the blast hole. When the air pressure on the bit is shut oif or the hole in the bit becomes jammed with rock the residue drops down in the blast hole and jams the flared cutting end as efforts are made to withdraw the bit.

High pressure air is the most effective and best known means of opening the blast hole and loosening the material which has caused the drill bit to jam. However, considerable difficulty is experienced in connecting a source of air having such high pressure to the end of a drill bit. A secure and safe connection with the end of the drill bit is of the utmost importance in this case because should the hose come loose from the drill bit it will whip around wildly causing considerable damage to equipment and perhaps serious injury to personnel in the vicinity. Also, the workmen are inclined to apply a force to the hose and the connection in an eiort to free the drill bit itself. Hence, the necessity of providing an extremely safe and secure connection with the end of the drill bit in order that the necessary air pressure may be applied to free the drill without causing injury or damage. The equipment must be simple, convenient to use, and portable in order that it may be moved along with the drilling equipment as the blast face drilling progresses. Of considerable importance in a device of this type is the fact that the device must be adaptable to at least the four main drill sizes as well as providing a tight connection with new drill steels and those that have been shortened and have had the lugs worn through repeated use.

Among the objects of the present invention are; to provide a device which can be easily, conveniently and ice safely used to free rock drill bits that have jammed within the rock face; to provide a device which will safely and securely connect the end of the drill bit to a source of high pressure air; and provide a device which is readily adaptable to eifect a secure connection with the several different sizes of drill steel as well as those which have been shortened and worn through repeated use.

Other objects will be in part apparent and in part pointed out specifically hereinafter in connection with the description to follow, in which:

Figure 1 is a longitudinal diametrical section showing the present invention with a drill steel connected therein and connected to a source of high pressure compressed air, parts of which have been broken away to conserve space;

Figure 2 is a side elevation showing the coupling device, hose connection and drill bit;

Figure 3 is a side elevation looking towards the left in Figure 2;

Figure 4 is a transverse section taken along line 4 4, Figure 3;

Figure 5 is a longitudinal diametrical section of the hollow cylindrical spacer element showing an adapter tube in place therein; and

Figure 6 is an end view showing the parts in inverted position with the locking member pivoted into open position to reveal the safety key in place about the shank of a hexagonal drill bit.

Referring now in particular to Figures 1 through 4 of the drawing, reference numeral 10 indicates in a general way the high pressure coupling device of the present invention connected by means of hose tting 11 to a source of high pressure compressed air. The hose fitting is removably secured by means of a threaded connection to the internally threaded outer end of hollow cylindrical spacer element 12. The cylindrical opening 13 within the spacer element is sized to receive the shank of the largest drill bit in common use and provided with an outwardly flaring portion 14 adjacent its inner end to guide the shank of the drill into the cylindrical opening. An annular raised portion 15 extends inwardly on the inner wall of the spacer element providing a stop for the inner end of drill bit 16 and a seat for hose gasket 17 and drill gasket 18 which prevent leakage of the high pressure compressed air around the drill bit. The inner end of the spacer element is externally threaded by which means said spacer element is connected for longitudinal adjustment within internally threaded connecter ring 19. The inner cylindrical wall of the connecter ring has an annular stop 2i) which prevents the spacer element from being threaded all the way through the connecter ring. The outer surface of the connecter ring contains at portions 21 on which are mounted for pivotal movement about pivots 22 lock member 23. The lock member comprises two substantially parallel legs 24 having openings adjacent their outer ends for the reception of the pivots. The inner ends of the legs are joined together by a circular lock plate integral with said legs and extending transversely with respect to the center line of the connecter ring in spaced relation to the inner end thereof. The lock plate is provided with an opening 26 extending from the center to the portion of the edge which is at right angles to the axis of pivoting of the lock member. As will be seen most clearly in connection with Figure 6, this opening permits the drill shank to be passed through the connecter ring into the spacer element with the lock member pivoted into the open position shown, the lugs 27 extending transversely from the shank of the drill bit being wider than the width of opening 26; whereupon, pivotal movement of the lock member into the closed position shown in Figures 1-4 will place the inner surface of the lock plate adjacent the opening therein in position to prevent Withdrawal of the drill bit. A circular recess 28 is positioned on the outer face of the lock plate surrounding opening 26 in which is inserted safety key 29. When the outer end of the drill bit shank is placed Within the spacer element until it abuts against the annular raised portion, the lock member is pivoted into position about the shank of the drill, the safety key positioned within the circular recess in the lock plate thus closing the opening in the edge of the lock plate, and the spacer element threaded into the connecter ring until the lugs on tile drill bit are forced against the safety key, the lock member cannot be opened nor can the drill bit be Withdrawn from Within the coupling device. This is the position of the elements illustrated in Figures 1-4. A hollow semi-cylindrical handle member 30 extends inwardly along the shank of the bit to facilitate opening and closing the lock member.

It can readily be seen that the above construction affords the positive and secure connection between the source of compressed air and the drill bit which will not come loose even though considerable force is applied to the coupling in an effort to assist the compressed air in freeing the bit. In the event that the shank of the drill bit within the spacer element is shorter than normal, either due to wear or manufacture, or the lugs are Worn, the adjustable connection between the spacer element and the connecter ring provides for considerable adjustment to be made in order to compensate for the peculiarities of the particular drill bit and thus produce a tight and safe connection with the air supply.

Referring now to Figure 5, in order to adapt the coupling device to use with all the conventional drill bits which have shanks of dilferent diameters as welt as lugs shaped and positioned differently, a set of adapter tubes 31 are provided. if an adapter tube is necessary, the spacer element is removed from within the connecter ring and the proper adapter tube is inserted within the inner end of the spacer element.

A set of safety keys are also provided to accommodate the different sized drill bits, the keys varying from one another only insofar as the opening between the iegs is sized to t the shank of the various bits.

When a drill bit becomes jammed within a rock face, the drill is disconnected from the normal source of air and connected with a source of high pressure air in the following manner. If necessary, the proper adapter tube is inserted within the spacer element and the spacer element threaded into the connecter ring. With the lock member in open position, the shank of the drill bit is passed through the connecter ring into the spacer element or adapter tube until it will go no further; at which time, the lock member is moved to closed position with the shank of the bit in the opening in the circular lock plate. The proper safety key is inserted over the drill shank in the space between the outer face of the lock plate and the inner face of the connecter ring and moved inward into the circular recess in the outer face of the lock plate closing that portion of the opening in the lock plate which communicates with the edge, thus locking the safety key and closing the opening. Then it is only necessary to screw the spacer element into the connecter Cil ring until the annular raised portion within the inner wall of the spacer element forces the lugs on the shank of the drill against the safety key to complete the connection. The high pressure air supply can then be connected to the outer end of the spacer element Without danger of the coupling device coming loose.

This application is a continuation in part of application Serial No. 172,154, tiled July 5, 1950 which is now abancloned.

lt will be seen from the above description of the invention claimed herein that the many advantageous results have been achieved by the construction shown in the accompanying drawing; and, therefore, I claim:

1. A high pressure coupling for use in connecting a rock drill bit of the type having lugs thereon to a conduit supplied with compressed air comprising: an internally threaded ring; a spacer element threaded within the ring for longitudinal adjustment relative thereto, said spacer element having a longitudinal opening sized to reccive the shank of a rock drill bit, said spacer element being provided with a stop projecting into the longitudinal opening in position to abut the end of a drill bit inserted therein, and said spacer element having means located at the end opposite the end in which the drill 1oit is insertedfor effecting connection with a conduit supplied with compressed air; means for holding a drill bit within the spacer element comprising a lock plate carried by the ring in position to form an abutment for the lugs on the drill bit as said lugs are moved in the direction of said plate by adjustment of the spacer element within the ring, said lock plate having an opening cornmunicating one edge thereof positioned and sized to receive the shank of the drill bit, and the portion of said lock plate bordering the opening therein and facing the spacer element being recessed to form a seat for a safety key; and an insertable safety key adapted to fit within the seat in the lock plate to close the portion of the opening in said plate communicating the edge thereof and thereby lock the drill bit within said opening, said key being held within the seat by the lugs on the drill bit forced against said key by adjustment of the spacer element.

2. A device in accordance with claim 1 in which: the lock plate is connected to the ring for pivotal movement from an open position in which the shank of the drill bit may be inserted and removed from the spacer element to a closed position in which the drill bit is retained within the spacer element by said lock plate.

References Cited in the tile of this patent UNITED STATES PATENTS 1,273,944 Smith July 30, 1918 1,486,662 Hamilton Mar. 11, 1924 1,503,932 Wilhelm Aug. 5, 1924 1,711,018 Ellis Apr. 30, 1929 1,747,741 Sprung Feb. 18, 1930 1,789,101 Hansen Jan. 13, 1931 2,269,659 Glowaski a- Jan. 13, 1942 2,281,633 Stitzer May 5, 1942 

